Fuel feed mechanism for internal combustion engines



Sept. 1, 1936.

J. ZUBATY FUEL FEED MECHANISM FOR INTERNAL COMBUSTION ENGINES Filed Jan.4, 1934 INVENTOR. c/05e 0/2 Zubat g B 1 572mg I,

ATTORNEYS.

Patented Sept. 1, 1936 UNITED STATES FUEL FEED MECHANISM FOR INTERNALCOMBUSTION ENGINES Joseph Zubaty, Prague, Czechoslovakia ApplicationJanuary 4,

15 Claims.

-Thisinvention relates to fuel injection systems for internal combustionengines and has particular reference to the manner of pumping andmetering the fuel delivered to the engines. Although this invention isparticularly adapted for that type of internal combustion enginegenerally designated as Diesel engines, it is not entirely limited tosuch a type but may also be advantageously applied to other types. Ithas been the custom in the past to deliver fuel to the combustionchamber of a Diesel engine under high pressure, and at the. same time toregulate the charge of fuel in order to vary the speedof the engine. Oneof the difficulties presented by such an arrangement is that under thehigh pressures developed and because of the high speed of the operatingparts it becomes exceedingly difiicult to accurately control the fuelcharge delivered.

It is an object of this invention to overcome the aforementioneddifiiculty by providing an improved fuel injection system which enableseasily and accurately controlled charges of fuel to be delivered to theinternal combustion en- 25 gines. This is accomplished by undertakingthe metering of the fuel, which operation requires the greatestaccuracy, at low pressures.

A further object of this invention is to increase the responsiveness ofthe engine to the control exercised by the operator, and this isobtained by providing an improved fuel and distributing pump havingoperating parts which may be machined with the utmost accuracy and Dwhich, if any wear takes the cylinders equally.

A further object of this invention is to provide a fuel pumping systemfor internal combustion engines which is economical to construct 40 andmaintain and which eliminates high pressure piping of the fuel therebydecreasing the likelihood of fuel leakage. Another object of thisinvention is to provide a fuel delivery system for intern-a1 combustionwhich combines a low pressure regulatable fuel pump and distributor withhigh pressure fuel injection devices in such a manner that the quantityof fuel is regulated at low and easily controlled pressures but isdelivered into the 50 cylinders under high pressures.

A still further object of this invention is to provide in a fueldelivery system of an internal combustion engine a fuel injection devicewhich is adaptable to receive already metered charges 35 place, willaffect all 55 of fuel and to automatically vary its fuel charge 1934,Serial No. 705,177 (01. 103-37) capacity directly in accordance with thereceived metered charges of fuel.

A meritorious feature of this invention is the fuel pumping system as awhole. The fuel is conducted from a fuel supplyto the internal 5combustion engine by a low pressure distributing pump and a plurality ofhigh pressure injection pumps associated with each cylinder of theengine. Control mechanism is associated with the low pressuredistributing pump for accurately determining the amount of fuel chargedelivered thereby, and this pump distributes this measured amount offuel under low pressure to the injection devices. These injection pumps.which are operatively connected with the engine, 15 force the measuredfuel that they have received at timed intervals and under high pressureinto their respective cylinders. The high pressure injection pump is soassociated with the operation of the lowpressure pump that it is adapted20 to vary the extent of its operation directly in proportion to themeasured charges of fuel received.

Various other objects and meritorious features of my invention willbecome apparent from the following description taken in conjunction withthe drawing wherein like numerals refer to like parts throughout theseveralfigures and wherem:

Figure 1 is a diagrammatic view of an inter- 3o nal combustion engineshowing a pair of adjacent pistons for driving the crank shaft and thedistribution of the fuel pumps with respect to the engine, I

Figure 2 is an enlarged view, partly in cross section, of the fueldelivery system showing in detail the operating arrangements of the lowand high pressure meansfor metering and injecting the fuel into thecylinders of the en- 40 gine, and

Figure 3 is a sectional view of a portion of the fuel distributing pumpshowing the manner of distributing the fuel from the pump.

In Figure 1 a diagrammatic illustration of an internal combustion engineincludes a crank shaft In about which are mounted a plurality of pistonrods as l2 and I4 for driving the crank shaft when the pistons l3 (andI5, to which the rods are connected, are moved by the pressure of theburning fuel. The pistons are mounted within aligned cylinders (notshown) and to each cylinder there is connected a fuel injection devicegenerally designated as I6. Associated with each of these fuel injectiondevices I 6 is a fuel distributing pump generally indicated at Ill. Thedotted lines extending from the distributing pump to the injectiondevice represent, diagrammatically, the manner in which the fuel isdis.- 5 tributed from the former to the latter. Both the distributingpump and the injection device are operatively connected .with the engineas shown in Figure l and as will be more fully pointed hereinafter. InFigure 2 a more detailed view of one embodiment of the invention isshown. The dotted line 26 indicates diagrammatically a fuel conduitextending, as shown by the arrows, from a source of fuel supply (notshown) to combus- 15. tion chamber 22 of an internal combustion engine.In this fuel conduit there are located a gear supply pump 24 forforwarding the fuel in the direction of the combustion chamber, a fuelfiltering mechanism 26, and the aforementioned fuel distributing pump l8 and injection device IS. The fuel inlet 28 into the combustion chamberis normally closed by the nozzle of a needle valve 38 of usual designwhich forms part of the injection device l6. The needle valve 30 isnormally held in closed position by the spring 32 seated at one endagainst a flange 34 on the needle valve and at the other end against anadjustable mounting 36. The spring 32 is normally so tensioned that forrelatively low pressures exerted on the nozzle of the needle itmaintains the latter in closed position, but when the pressure reaches apredetermined relatively high pressure the spring yields allowing thevalve to open. a Fuel is delivered through the passage 38 and a 35(chamber located adjacent the nozzle of the needle valve 36.Communication is established between the chamber 40 and the inlet 28when the needle valve is opened under pressure of the fuel in thechamber 40. Mechanism for exerting 40 a pressure on the fuel to open thevalve 36 is provided in the form of a compression chamber 42communicating directly with the passage 38 and a reciprocating pumpplunger 44 operable within the compression chamber. The pump '45 plunger44 is operatively connected with the engine as will be more clearlydescribed hereinafter. Fuel is delivered into the compression chamber 42through the passage 46 of the injection device l6. A pair of checkvalves ,48 prevent the 50 fuel under pressure in the compression chamberfrom returning back into the fuel lines. Each of the passages 46 of theinjection devices is in communication with one of the discharge outlets50 of the fuel distributing pump I 8. The discharge outlets 58 are shownarranged in a circular formation as indicated in Figure 3, andassociated with each of these outlets is a pumping chamber 52 and aplunger 54. Fuel is delivered to each of these pumping chambers 52through 60 the inlet 56 which is connected with the fuel line leading tothe fuel supply. A number of check valves 58 are disposedwithin thecommunicating passages of the. fuel distributing pump I8 for forwardingthe fuel in the direction of the fuel injection devices I 6. a A shaft68 is disposed along the axis of th circularly arranged pump plungers54. A cam plate 62 is pivotally mounted on the shaft 66 by the pin 64.The opening 65 in the cam plate 70 through which the shaft 60 extends isof a considerably larger diameter than the latter, and it is readilyapparent that the cam plate may be tilted to a number of planesangularly displaced with respect to the shaft. As shown in Figure 2 7the cam plate engages the exposed end ofthe plungers 54, and the latterare constantly maintained in contact with the cam plate by means of thesprings 66. Means for tilting the cam plate 62 are provided in the formof an axially slidable collar 68 which is slidable for a portion of thelength of the shaft in the keyway I0. Pivotally connected between thecollar 68 and the cam plate 62 is a link 12 which transfers the axialmovement of the collar to the edge of the plate tilting the latter withrespect to the shaft 60. A bifurcated control mechanism of any suitabledesign could readily engage and move the collar 68 and thereby tilt thecam plate to pump.

In the embodiment illustrated herein, both the fuel distributing pumpand the injection device are driven from the engine. This drivingrelation is diagrammatically represented in Figure 1 where a gear wheel14 on the crank shaft I8 is geared to a larger gear 16. The latter inthis figure is adapted to be driven at half crank shaft speed. Mountedon the same shaft as the gear 16 is the gear 18 which engages gear 88fixed to the shaft 60 in Figure 2. Also mounted on the said shaft as thegears 16 and 18 are the cams 82 which are adapted to rotate at halfcrank shaft speed and operate the plungers 44 in the fuel injectiondevice. This is merely illustrative of a driving mechanism for thispurpose.

Mechanism extending fromeach cam 82 for actuating the pistons 44comprises a lifter 84 to which is secured a roller 86 adapted to becontacted by the cam, and a push rod 88 for transmitting the motions ofthe lifter to the piston. A flange 90 is provided on the lifter 84 andbetween the flange and a portion of the cylinder housing there ismounted a spring 92 which supports the weight ofthe push rod 88 and thepiston 44 and normally spaces theroller 86 from the less cammed portionsof the cam 82 as shown in Figure 2. The spring 92 is yieldable to fuelpressures in the compression chamber 42, and in so yielding. it lowersthe piston 44 increasing the volume of the compression chamber. Theextended portion of the cam 82 is adapted upon rotationto contact theroller 86 and force the piston through the medium of the lifter and pushrod, up into the compression chamber. I

In the operation of the device disclosed herein,

' both the fuel distributing pump and the fuel injection devices aredriven by the engine. The up and down motion of the plungers ,54 in thedistributing pump is obtained from the tiltedcam plate 62 which rotateswith the shaft 68. Since the same plate actuates each of the plungers,they all discharge the same quantity of fuel, and any variation in theangle of the plate affects the operation of all of the plungers in thesame propor-- tion. The fuel discharged by each plunger is delivered toits respective cylinder under relatively low pressure. This is, due tothe fact that the tilt of the rotating plate 62 forms a gradual cammedsurface forcing the plungers through the chambers 52 at a comparativelyslow speed.

The measured charge of fuel discharged from any one of the pump chambers52 is delivered to the compression chamber 42 and the chamber 40 under apressure insuflicient to raise the needle valve 30 fromits seat.However, the pressure of the fuel within these chambers is suflicient tocompress the spring 92 and as a result the volume roller 86, the piston44 is forced deep into the chamber 42 compressing the fuel therein andbuilding up sufiicient fuel pressure to lift the nozzle of the valve 30from its seat allowing the fuel to be injected into the combustionchamber 22.

To vary the delivery of fuel the collar 68 is moved axially along theshaft 60 changing the plane of the cam plate and increasing ordecreasing the extent of the plunger movement. The

cam plate is merely a fiat disc and can be machined with extremeaccuracy. The plungers of the distributing pump move comparativelyslowly and develop relativelow fuel pressures thereby rendering possiblethe extremely exact metering of the fuel. Because of the low pressure ofthe metered fuel the conduit conducting the fuel may be small sectionedthin walled tubing. The only high pressures developed in the fuel lineoccur adjacent the combustion chamber, and, as shown in Figure 2, shortbut relatively stronger means may be employed for sustaining thesepressures.

Various modifications of my improved mechanism will be apparent to thoseskilled in the art and for this reason I intend to'limit myself onlywithin the scope of the appended claims.

What I claim:

1. Fuel delivery mechanism for an internal combustion engine,comprising, in combination, a relatively low pressure metering pumpoperable to deliver variable charges, a relatively high pressure forcepump communicating with the metering pump to receive metered chargestherefrom and adapted to deliver said charges under relatively highpressure, a piston in said high pressure pump means adapted to drivesaid piston at certain intervals of time and resilient means spacingsaid piston from said driving means a distance inversely varying as thequantity of the charge delivered by said low pressure pump.

2. A fuel delivery system for an internal combustion engine comprising,in combination, a low pressure variable delivery fuel pump, a highpressure fuel pump adapted to receive variable charges of fuel from thelow pressure pump and deliver the same under relatively high pressure, apiston in the high pressure pump, means adapted to act directly uponsaid piston to discharge the fuel from said high pressure pump, andresilient means spacing said piston from driving contact with said meansin the interval of time between the pump operations of said piston, saidresilient means being yieldable to varying charges received by the highpressure pump to position the piston at varying distances from saiddriving means prior to each pumping operation.

3. A fuel delivery system for an internal combustion engine comprising,in combination, a fuel line, a relatively low pressure variable deliveryfuel pump in said fuel line adapted to deliver variable quantities offuel therethrough, a relatively high pressure fuel pump in said fuelline between said low pressure pump and the discharge end of the fuelline adapted to act on the variable charges of fuel in the line andconvey the same under relatively high pressure, said high pressure pumphaving a reciprocating plunger therein, a cam adapted to act upon saidplunger to deliver pumping strokes thereto, and a spring resilientlyspacing said plunger from said cam except when said cam is acting todrive said plunger said spring yieldable under variable chargesof fuelreceived by the high pressure pump to vary the length of the stroke ofthe plunger.

4. Liquid delivery mechanism comprising, in

fuel therefrom under relatively combination, a low pressure meteringpump, a high pressure pump communicating therewith to receive variablecharges therefrom, driving mechanism for the high pressure pump, saiddriving mechanism including means yieldable to the metered chargereceived to vary the length of the delivery stroke of the pump directlyas the received metered charge varies in quantity.

5. Fuel delivery mechanism for an internal combustion engine comprising,in combination, a relatively high pressure fuel injection device havinga compression chamber and a piston reciprocable therein, a low pressurefuel metering device communicating with said compression chamber andoperable to deliver measured charges of fuel thereto under relativelylow pressure, means for positively driving said piston intermittentlythrough said compression chamber to discharge high pressure, and meansyieldingly tending to urge said piston into said compression chamber andresponsive to the pressure of the fuel charges delivered by saidmetering pump to permit said piston to yield and vary its initialposition prior to its movement through the compression chamber.

6. Fuel delivery mechanism for an internal combustion engine comprising,in combination, a

1 means adapted at timed intervals to move said plunger and exertpressure on the fuel in said compression chamber sufficient to open saidvalve and discharge the fuel therethrough, means yieldingly mountingsaid plunger and adapted at other than said timed intervals to permitthe plunger to yield to the pressure of the fuel in the compressionchamber as it is delivered thereto by said metering device whereby thevolume of said injection device may be automatically varied by the lowpressure metering pump prior to each fuel injection operation.

7. Fuel delivery mechanism for an internal combustion engine comprising,in combination, a fuel compression chamber, means for delivering meteredcharges of fuel thereto, a plunger reciprocable in said compressionchamber adaptedto eject fuel therefrom, means operable at certainintervals of time to drive said plunger through said compressionchamber, and resilient means yieldingly urging said piston into saidcompression chamber and providing a lost motion drive relationshipbetween said driving means and said plunger.

8. Fuel delivery mechanism for an internal combustion engine comprising,in combination, a fuel compression chamber having a discharge passage, avalve controlling said passage, a spring urging said valve to closedposition, a plunger 'mounted for reciprocable movement in said coma fuelline, a normally closed control valve in said fuel line responsive to apredetermined fuel pressure to open and permit passage of fuel thereby,

a fuel pump in said fuel line adapted to deliver variable charges offuel therethrough under pressure insufiicient to open said controlvalve, a fuel injection mechanism in said fuel line adapted to receivesaid variable charges of fuel, said injection mechanism having a partyieldable to the pressure of said variable charges of fuel to increasethe volume of the injection mechanism in accordance with the pressure ofthe variable charges of fuel received, and means operable to drive saidfuel injection mechanism at timed intervals and at sufiicient pressureto cause the fuel discharged thereby to open said control. valve andpass thereby.

10. A fuel injection device comprising, in combination, a pump chamberhaving a fuel inlet and a fuel discharge outlet, a plunger reciprocablein said chamber, means operable to move said plunger at timed intervals,and resilient means yieldiingly spacing said plunger from operativeassociation with said means except when the latter functions to movesaid plunger, said resilient means permitting said plunger to yield tothe pressure .of the fuel, introduced into said pump chamber.

11. A fuel injection device including a reciprocating part, means fordelivering pumping strokes to said part, and a spring yieldingly spacingsaid part from operative relationship with said means in the intervalsof time between the action of said pumping strokes.

12. Drive mechanism for a fuel injection device including means fordelivering pump strokes, a member adapted to receive said strokes, and aspring engaging said member and yieldingly supporting the same exceptwhen said means is delivering said pump strokes.

13. A fuel injection apparatus comprising, in combination, a fuel pumpincluding a compression. chamber and a piston reciprocable therein,means for intermittently driving said piston through said chamber toeject fuel therefrom, and a spring yieldingly restraining said pistonfrom rearward movement between said ejection operations to permit thepiston to yield to the pressure of the fuel introduced into said chamberprior to each ejection operation.

14. A two stage fuel delivery system comprising, in combination, a lowpressure metering fuel pump having a fuel chamber and a plungerreciprocable therein, a relatively high pressure fuel injection pumphaving a. fuel compression chamber and a plunger reciprocable therein,fuel conduit means connecting said chambers and adapted to convey themetered charges of fuel discharged by'said low pressure pump to thechamber of said high pressure injection pump, means proportion to thesize of the fuel charge delivered thereto by said low pressure pump.

15. A fuel delivery system comprising, in combination, a relatively highpressure fuel injection pump having a. fuel compression chamber and aplunger reciprocable therein, means for intermittently feeding fuelcharges into said compression chamber, means for varying the size of thefuel charges thus delivered, means for driving said plungerintermittently through said chamber to eject fuel therefrom underrelatively high pressure, and means rendering said plunger yieldable tothe pressure of fuel in the compression chamber as it is deliveredthereto whereby said plunger will yield to the fuel charges delivered tothe compression chamber in direct proportion to the size of the fuelcharges.

JOSEPH ZUBATY.

